Manufacture and production of oxalic acid



15 wood with nitric acid,

80 this purpose.

30 about 60 degrees centigrade.

' rate the cellulose,

Patented Dec. 9, 1924.

unrrso AL'WIN MITTASCH AND OTTO BALZ,

ASSIGNOBS 'I'O BADI$GHE ANILIN- BHINE, GERMANY, A CORPORATION PATENTOFFICE.

F LUDWIG$HAFEN-ON-THE-RHINE, GERMANY, & SGIJA-FABBIK, 0FLUDWIGSHAFEN-ON-THE- 0'5 GERMANY.

MANUFACTURE BN3) PRGBUGTIGN DE @XALIC ACID.

No Drawing. Apuiicetion me To all whom it may co /warn:

Be it known that we, ALWlN hlrr'mscn and Orro BALZ, citizens oi Germany,residing at Ludwigshafen-on-the-Rlnne, Gen

5 many, have invented new and useful improvements in the Ii-Ianu'iactureand ,Production of Oxalic Acid, of which the following; is aspecification.

As is known oxalic acid is formed by the action of nitric acid on wood,but the The invention is more fully explained with reference to thefollowing examples to which however the invention is not limited. Wood,in small pieces, soaked in a solution of iron nitrate and treated with acura temperature of The wood is uickly dissolved, and after a period oftime, which may be ascertained by preliminar experiments for theconditions chosen, the mixture is filtered, while hot, to sepa-. whichremains unattached, or high molecular decomposition products thereof,whereupon the oxalic acid-which is chiefly produced from the so-calledincrustrent of nitrous gases at august 1%, 1921.

Serial No. 493,651.

ing substances of the wood-is caused to crystallize from the filtrate bycooling and is then obtained by centrifuging. The mother liquor is usedfor soaking a fresh quantity of wood and the treatment with nitrousgases is repeated. The reaction liquor may also fore crystallizing theoxalic acid or it may he used for repeated treatment or wood beforeseparating the oxalic acid. Nitricl acid of suliicient strength may beused instead of nitrous gases, in which case the wood may be treatedwith nitric acid containing iron nitrate, while stirring, and thenworked up in the manner already described.

The ferric liquor separated from the oxalic acid may be used again afterfresh nitric acid has been added. The temperature should not, generallyspeaking, be allowed to 2 s above about 70 degrees centigradc. Theescaping gases, containing lower oxids of nitrogen, can be absorbed withwater to.

form nitric acid in the usual way after being suitably oxidized and thenitric acid can then be used again. The process can also be made acontinuous one.

1. The process of producing oxalic acid which consists in acting on woodwithnitric acid in the presence of an iron. compound.

2. The process of producing oxalic acid which consists in heating woodwith nitric acid in the presence of ferric nitrate.

In testimony whereof we have hereunto set our hands.

ALWIN MITTASCH. OTTO BALZ.

be evaporated in vacuo be-'

